1. Field of the Invention
The present invention relates to a plasma display panel (hereinafter abbreviated PDP), and more particularly, to a barrier rib of a plasma display panel and forming method thereof, by which costs for fabricating the barrier rib are reduced and the fabricating method is simplified.
2. Description of the Background Art
Lately, many efforts are made to study and develop such a next generation digital multimedia display device as LCD (liquid crystal display), FED (field emission display), PDP, ELD (electroluminescent display), etc. Specifically, many attentions are paid to PDP that is more advantageous than others.
The PDP is a display device using light-emission generated from phosphors of R, G, and B excited by a 147 nm UV-ray radiated by (He+Xe) or (Ne+Xe) gas discharge in a discharge cell provided by a barrier rib. The PDP is a large-sized (over 40″) screen display device having such many advantages as facilitated fabrication due to simple configuration, high brightness, high efficiency, memory function, high non-linearity, wide viewing angle over 160°, etc.
A barrier rib of a three electrode AC surface discharge type PDP and fabricating method thereof are explained in detail by referring to the attached drawings as follows.
FIG. 1 is a cross-sectional view of a discharge cell of a three electrode AC surface discharge type PDP according to a related art.
Referring to FIG. 1, a discharge cell of the PDP is formed by combining a front plate 100 and a back plate 110 and by injecting discharge gas between the front and back plates 100 and 110.
The front plate 100 consists of an upper glass substrate 101, transparent electrode 102 and bus electrode 103 formed on the upper glass substrate 101, an upper dielectric layer 104 formed on the upper glass substrate 101 including the transparent and bus electrodes 102 and 103 formed thereon, and a protection layer 105 formed on the upper dielectric layer 104 to protect the upper dielectric layer 104 from plasma discharge.
The back plate 110 consists of a lower glass substrate 116, an under layer 115 formed on the lower glass substrate 116 to prevent penetration of alkali ions contained in the lower glass substrate 116, an address electrode 114 formed on the under layer 115, a lower dielectric layer 113 formed on under layer 115 including the address electrode 114, a barrier rib 111 formed on the lower dielectric layer 113 to form a discharge cell, and a phosphor 112 formed on the lower dielectric layer 113 and the barrier rib 111.
In this case, the barrier rib 111 plays an important role in preventing electrical and optical cross talk between discharge cells. The barrier rib 111 is mainly formed of ceramic or glass-ceramic. A width of the barrier rib 111 is 70˜100 μm and a height of the barrier rib 111 is 120˜200 μm. 80% of an overall thickness of the barrier rib 111 is formed of a highly reflective white paste layer 111B containing TiO2 or Al2O3 as a filling agent and the rest 20% is formed of a black paste layer 111A enabling to absorb external light effectively.
The above-constructed barrier rib 111 is formed by screen printing, sandblasting, or additive method. A method of forming a barrier rib of PDP using sandblasting is explained by referring to the attached drawing.
FIG. 2 is a flowchart of a method of forming a barrier rib of PDP according to a related art.
Referring to FIG. 2, a method of forming a barrier rib of PDP includes the steps of forming a white paste layer and a black paste layer on the glass substrate successively (S21), forming a DFR (dry film resist) layer on the black paste layer (S22), forming a DFR pattern by patterning the DFR layer into a predetermined figure (S23), removing portions of the black and white past layers failing to be covered with the DFP pattern (S24), and removing the DFR pattern and plasticizing the remaining black and white paste layers to form the barrier rib (S25).
A method of forming a barrier rib of PDP according to a related art is explained in detail by referring to FIGS. 3A to 3E as follows.
FIGS. 3A to 3E are cross-sectional views of a method of forming a barrier rib of PDP according to a related art.
Referring to FIG. 3A, each of the white paste layer 310A and the black paste layer 310B is formed on the glass substrate 300 by printing to have a predetermined height (S21). In this case, the glass substrate 300 includes the lower glass substrate 116 on which the under layer 115, address electrode 114, and lower dielectric layer 113 are successively formed.
The white paste layer 310A is formed in a following manner.
First of all, several-tens % of TiO2 or Al2O3 powder having a particle diameter below 2 μm for improvement of reflection property and adjustment of dielectric constant is mixed with PbO or non-PbO glass powder having a particle diameter of 1˜2 μm to form mixed powder. The mixed powder is then mixed in an organic solvent to form the white paste 310A of a paste phase having a viscosity of 40,000˜50,000 cps.
The black paste layer 310B is formed in a following manner.
First of all, several % of black pigment for absorption of external light is mixed with PbO or non-PbO glass powder having a particle diameter of 1˜2 μm, and is then mixed with several % of Al2O3 powder having a particle diameter of 2˜3 μm for rigidity maintenance to form the black paste layer 310B of a paste phase having a viscosity of 30,000˜4,000 cps on the white paste layer 310A. And, the black paste layer 310B is dried at 100˜150° C.
Referring to FIG. 3B, the DFR layer 320 is formed on the black paste layer 310B by laminating (S22).
Referring to FIG. 3C, a mask (not shown in the drawing) is formed on the DFR layer 320. UV-ray exposure and development are carried out on the DFR layer 320 having the mask formed thereon to form the DFR pattern 320A (S23).
Referring to FIG. 3D, portions of the black and white paste layers failing to be covered with the DFR pattern 320A are removed by sandblasting (S24).
Referring to FIG. 3E, the DFR pattern 320A is removed by alkali solution. The remaining black and white paste layers 310B and 310A after sandblasting are dried at 100˜150° C. and plasticized to form the barrier rib 310 of the PDP (S25). In this case, the plasticization is carried out at 550˜600° C., and density of internal structure of the barrier rib varies according to compositions and contents of the glass and filling agent.
As mentioned in the foregoing explanation of the related art method of forming the barrier rib of the PDP, the barrier rib is formed using the DFR pattern formed on the black paste layer, whereby fabrication costs of the barrier rib of the PDP are increased.
Moreover, when the DFR pattern is removed in the alkali solution, water contents and alkali ions may penetrate into the barrier rib to produce impurity gas in the discharge space. Hence, the related art method of forming the barrier rib of the PDP needs an additional step of drying the water contents at 100˜150° C.